A battery box should not change the tonal balance of your recordings.
It should give you the ability to record things that are louder without distortion. If the bass is distorting/overloaded then yes a battery box should help (see below for more details).
For medium to large venues the best way to achieve less bass is to be close to the stage. The further back you are the bassier it will sound. More than halfway back almost no mics will not sound bassy.
Small mics like these often tend to deemphasize the bass so if your results still seem bassy there's not a lot you're likely to be able to do other than improve your position or adjust it after the fact.
So you might want to make some adjustments in post-processing (filter and/or eq to compensate).
As SP says about battery boxes/powering on their site:
Powering Options:
There are several ways to power these microphones. Each of these options provides the same sound quality, the only difference is the maximum sound pressure level (SPL) the mics can handle.
1-The microphones can be powered with normal "plug-in-power", available on many portable recorders and camcorders. With this type of power, the mics will handle reasonable sound levels. If you will be using the mics in high SPL (sound pressure level) situations, the microphones require additional power, beyond the normal "plug in power". You will need to use one of the powering schemes described below:
2-For strong sound levels, consistent with loud amplified concerts, you can add battery module for increased high SPL performance and dynamic range. You can select the battery module shown above in the option box, or choose one of the many other types that are available on this page if you prefer. We also recommend that you add the "Low sensitivity" modification as an option (details on this option here).
3-However, if your recorder/mixer, etc. supplies phantom power, you can add the high SPL modified XLR connector option. Each mic has it's own XLR connector and cable and microphones ordered this way will not work with "plug in power" or standard battery module as shown above.
4-For intensely loud situations, consistent with highly amplified concerts at close distances to the speakers, you can add set of Ultra high SPL power modules (AT8538 or AT8531) with locking connectors between the mics and the power modules. In this configuration, the mics remain balanced. With the AT8538 modules, the microphones will plug into device (mixer, mic preamp, recorder, etc) that supplies 9-52v phantom power. With the AT8531, the microphones will run on each modules standard AA battery or 9-52v phantom power. This configuration provides the highest level of SPL capability. The output of the modules are XLRM plugs. To connect the portable recorder with miniplug input, select this cable.
Lastly, if you wish to use the mics with plug in power and phantom power (alternately), order the mics as shown in option "1" above and order this cable with the phantom power option.